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Stereo codecs extend battery life in portable audio apps

Posted: 03 Sep 2007 ?? ?Print Version ?Bookmark and Share

Keywords:stereo codecs? battery life? portable audio?

Leadis Technology Inc. has unveiled a family of audio codecs using its Gmax amplifier technology that promises to increase power efficiency, maintain best-in-class SNR and extend battery life in portable audio applications. The codecs are suitable for smart mobile phones, portable media players, portable gaming devices, GPS and digital still cameras.

The LDS9350 integrates a low-power and low-noise stereo codec, a highly efficient Gmax stereo headphone amplifier, an integrated stereo FM transmitter and a DC/DC converter in a single compact solution. Device features include:

Codec and headphone amplifierThe 3.3V 2-channel 24bit DAC exceeds portable audio noise requirements with an SNR of up to 102dB and can operate with sampling rates between 8KSps and 192KSps. The codec has multiple analog inputs including stereo microphone, stereo line and a fully differential mono microphone. Other features include programmable gain, line and microphone inputs, microphone bias and a low-power analog bypass mode. The chip also features high-fidelity audio outputs to either stereo headphones or to a stereo FM radio via the FM transmitter. Design innovations dramatically reduce system parts count and BOM cost while providing programmable control features for optimal audio quality.

FM transmitterThe LDS9350 provides an FM transmitter function with no additional external components. FM radio bands are selectable for worldwide operation: 87.5MHz to 108MHz for the United States and Europe, and 76MHz to 90MHz for Japan. Pre-emphasis and transmit power levels are programmable to meet country-specific regulatory standards. Advanced radio techniques deliver professional FM broadcast audio quality. Audio to the transmitter can be digital via I?S or analog via line-in and stereo microphone inputs. Chip operation is conveniently controlled through an I?C or a 3-wire microprocessor interface.

DC/DC converterThe LDS9350's highly integrated architecture includes an on-chip DC/DC converter that can be configured as a voltage booster or divider to generate system voltages and eliminate the need for external voltage regulators. The LDS9350 can be powered from a single supply and still maintain very low power consumption. In addition, the flexible clock PLL accepts and generates many standard audio frequencies, eliminating the need for multiple crystals.

The LDS9302L includes the Gmax headphone amps and provides all the same codec functionality and performance as the LDS9350 but without the on-chip FM transmitter. In addition, the device requires a single 1.8V power supply, which is important for applications with lower supply voltage.

"Our Gmax-enabled codecs need only 4mW of power for quiescent playback," said Tim Massey, VP and general manager of the Leadis Audio Business Unit. "More importantly, the Gmax amplifier technology really shines when comparing the power consumption at average listening levelssomething few chip manufactures are willing to specify. We specify power consumption at average listening levels to provide a real world estimate of battery life and to demonstrate the significant power saving capability of the Gmax amplifier technology. This translates to 50 percent lower system power consumption at typical listening levels and doubles the battery life of high-fidelity audio playback."

The LDS9350 and LDS9302L are sampling now and will be in volume production in Q4 2007. Both are packaged in a standard 40-pin 6mm x 6mm QFN package. Single-unit pricing for 1,000-piece purchases is $3.85 for the LDS9350 and $2.75 for the LDS9302L. An immediately available turnkey evaluation module includes a PC-based interface for easier programming and reducing time-to-market.

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